1. Field of the Invention
The invention relates to a method and an arrangement for protecting information in a memory element.
2. Description of the Related Art
Many modern electronic devices, such as mobile telephones and microcomputers, contain integrated circuits that are also called microcircuits. These integrated circuits have enabled a significant increase in the performance of electronic devices during the recent years and decades. More and more components are compressed in integrated circuits, which enables an increase in the memory and data processing capacity. The continuous increase in the integration degree is mainly due to the diminished size of the components used in the microcircuits brought about by the advancement in manufacturing technology. Further, when the size of the electronic devices diminish, the integration degree of the microcircuits must be increased, in other words the number of components to be positioned in the same package must be increased. The intention can even be to integrate a whole functioning data processing system, for instance the central functions of a mobile phone, on the same chip. For the reasons of cost-effictiveness, the intention is to use as many prefabricated components as possible and to avoid client-specific components.
Electronic devices frequently have at least one, but usually more memory elements, in which data relevant for the function has been saved. This data is essential from the point of view of illegal copying, i.e. piracy, so that its protection for instance by encrypting is very important for the legal manufacturer of the device.
Further, if several ASIC (Application Specific Integrated Circuit) components are to be positioned in one microcircuit package along with memory elements, the central processing unit, i.e. the CPU, and other data processing elements, the protection of the data is problematic, because the protection must not disturb the internal functioning of the microcircuit, but it must provide sufficient protection against illegal copying of data.